ZF6 -650 rebuild and other things I've done on my early 99 7.3 F350

[Dave_Nevada]

Well, I did just do the clutch 6 months ago, but it had started this noise before then. I used the pilot bearing sleeve fix...I know I know, not the best though it seemed to fit real well. I put an extra light layer of bearing lube on the bearing before install (not enough to affect the clutch in any way). When I have to do this again, I will use the Oil Lite bearing for sure.

As far as fluid, I did the overfill from the top of the trans and used Schaeffer's All Trans, which is Mercon V compatible. I am hoping the 256k miles hasn't taken it's toll. I guess I'll just keep going with it and maybe change my fluid one more time before this next trip. What fluid are you using? Maybe that Schaeffers isn't the best, though its a good fluid?

Thanks for taking the time on your thread to address my concerns! Much appreciated!

I just use Mercon 5. That's what the trans was designed for, and since I don't have millions to do detailed research on viscosity, contaminants, thermal-dynamic flow characteristics, particulate suspension properties, i'll just trust those guys. :drool:

 

[Dave_Nevada]

Well, after several months of running my rebuilt ZF6, it's still good and I'm happy with it. The solid bronze bearing has given me no trouble, along with the modified pedal tree.

However, one fly in the ointment is the throwout bearing arm. It looks like it's bent, because I measured the distance from the bellhousing to the dimple in the arm and it's just shy of 4.5". That's exactly the length of the slave pushrod length reach I measured back when I had the thing all apart. The symptoms started to show up one day when the trans was a bit hard to get out of gear. The clutch pedal isn't mushy, but you can tell you're bottomed out and the trans won't shift from gear to gear like it's supposed to.

I made this measurement when everything was brand new and I had 1.94" of room to operate from the bellhousing to the clutch fork dimple. That particular distance grew to exactly the measured distance of the slave pushrod. That means the arm has bent to the maximum reach of the slave cylinder pushrod and there's no wishing it away.

Well crap. Looks like I'll be pulling the trans to replace that arm. This time, it's going to get some reinforcing steel rod welded on it's back side so this crap doesn't happen again.

This also gives me an opportunity to inspect the solid bronze pilot bearing and to inspect the Valair HD clutch and throwout bearing. I'll check the bolts on the up-pipes I installed from Riff-Raff while I'm down there.

Oh well. At least everything is nice and clean under there and it won't be such a hassle to work on it.

Film at 11.

 

[Dave_Nevada]

Okay, I have the transmission back in now. It was the clutch fork that broke. I replaced it with the OEM upgraded fork from the 2001-2003 7.3.

I also welded in a fill plate in the factory stamped hole and stitch welded two steel rods under the rib folds. It's very solid now, even tried bending it with my hydraulic press, it took quite a bit of pressure to even make it flex. It should be good to go now.

I also inspected the input shaft for wear and the solid Oilite bearing- no issues at all. I re-installed the trans and am almost done with re-installing the exhaust. :thumbup:

Everything else looked great under there. I originally painted the driveline, clutch fork and the trans with Hammerite Rustoleum, and all were a pleasure to work on. No mess whatsoever. Clean as a whistle under there.

 

[blocknitup]

This better be stickied

 

[HyampomJ10]

I'm reviving this jewel of a thread for the new year!

What a wealth of information and knowledge. If only the internet had more people like Dave_Nevada.

I'm posting in the hopes that Dave_NV gets an email and looks at the forum to see my thanks to him. Also, it may be a long shot, but if he could give an update on his oilite pilot bushing. I'm gearing up to reman a zf6, and am curious about the long-term performance of the pilot.

Seems he hasn't been on since this thread was active. My fingers are crossed.

 

[psduser1]

I've run an oilite bushing in my 2000 for about 120k miles. It's been replaced once.
My truck is used and abused daily, not babied at all.
I'd never go back to kevlar or roller bearing style bushings.

 

[Barnbuilder]

Put the oilite bushing in mine several months ago. Also rebuilt clutch pedal with oilite bushings.

 

[HyampomJ10]

Good to hear, thanks for the info :toast:

 

[97vanswap]

Countershaft gear removal with steel tube and a press

When you are at the stage of removing the countershaft gears from the intermediate housing, let me caution you on one thing: the manual says to use hooks to attach to the cross cast aluminium arms and extract the race and gears from the shaft.

For me, that's not such a good idea. Pulling up on one of those cast arms will break something eventually and that Intermediate housing isn't cheap.

So I devised a safer method of pressing the gear and race off by using my 20 ton press and a steel cylinder I bought from a local supplier that is a schedule 40, 6" x 18" ($50.00).

I put a piece of foam cushion in the bottom of the tube, lowered the entire countershaft gear set into the tube, placed two pieces of 1 x 1 steel bar under the Intermediate housing (spreads the load around), and mounted the entire assembly in the press.

Viola!! The dude came out liked greased goose crap. This really helped with other gears and removal, but this was significant.

Nothing was damaged, which is the point.

Others may scoff at this, but it worked very well for me; I'll do it again this way.

Could s thin jawed t bar puller get behind that syncro body and press it out like that or would syncro body break?

 

[97vanswap]

Yeah, I though about the cutoff wheel approach. But I also know O'Tooles law would have bit me hard in the 6, and I would have slipped and buggered the mainshaft.

Plunk down another 350 bones for a new mainshaft. Arg! So MONEY (or me not wanting to spend it) is the main reason I thought of the tube.

Choice time: $50 for sure, or possibly $350. I saw $50 as an 'insurance fee'.

Hell, I buy insurance to replace what I cannot afford to buy outright, don't you?

If you score a mainshaft, you're screwed if you want to run that dude under a load. Those mainshafts are case hardened in the factory, which means, if you gouge them, that's the place it will break under load.

Case hardening will harden the surface for wear purposes but leave the core somewhat flexible to prevent stress cracks from torsional load forces.

Thus, the only difference between the 7.3 ZF6-650 regular mainshaft and the 6.0 ZF6-750 mainshaft is the case hardening depth. The 6.0 mainshaft is tougher than the 7.3 mainshaft (by design).

Ceramic tile can break at the score on its surface, just like glass and any other hard surface. Same idea with a case hardened metal.

That said, I'm also one that had the time to figure out lots of 'workarounds' when rebuilding the trans. I brought my 2000 'X' out of mothballs to act as my ride for the interim. but I also recognize not everyone can do that.

Do you mean countershaft? I think countershaft is what ya got in the tube.